1. Field
Aspects of the present invention relate to an electrode assemblage and a rechargeable battery, and more particularly, to an electrode assemblage with an improved electrode structure as well as a rechargeable battery using the same.
2. Description of the Related Art
A rechargeable battery differs from a primary battery in that the former can be repeatedly charged and discharged, while the latter only performs irreversible conversion of chemical energy to electrical energy. A small-capacity rechargeable battery is used as a power supply for small electronic devices, such as cellular phones, notebook computers, and camcorders, while a large-capacity rechargeable battery is used as a power supply for driving motors or as a power storage battery in hybrid vehicles and the like.
A large capacity high power rechargeable battery using a non-aqueous electrolyte with a high energy density has been recently developed. The large capacity high power rechargeable battery is constructed with a high power battery module having a plurality of rechargeable cells coupled to each other in series such that the battery can be used in electric vehicles requiring high power. The rechargeable battery may have a cylindrical, prismatic, or pouch shape.
With the rechargeable battery, an active material is coated on first and second electrode current collectors, or an active material sheet is laminated on the current collectors. Compared with the coated electrode, a laminated electrode may have a relatively large thickness. Further, as the contact area between the substrate and the active material layer is relatively small, when the thickness of the laminated electrode increases, the resistivity thereof also increases. With charging and discharging operations, electron transmission and ion transmission simultaneously occur, one of which may determine the charging and discharging speed. Even with a thick electrode, if the electrolyte saturation reaches equilibrium within a sufficient period of time, the speed depends upon the electron transmission reaction of the thick electrode.
In order to increase the conductivity of the active material layer, it is possible to increase the density of the mixture used for coating or to increase the content of the conductive agent. However, if the mixture density is increased, it is liable to obstruct the fluid saturation of the electrolyte, while if the conductive agent content increases, the battery capacity may be reduced.
As described above, when the thickness of the active material layer is increased so as to construct a large capacity rechargeable battery, the migration distance of electrons and ions is increased and the cell resistance is increased so that it is no longer possible for charging and discharging to be conducted at a predetermined C-rate or more.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form prior art that is already known in this country to a person of ordinary skill in the art.